Epitaxial structure of semiconductor device and manufacturing method thereof, and semiconductor device

Abstract

Embodiments of the present invention relate to an epitaxial structure of a semiconductor device and a manufacturing method thereof, and a semiconductor device. The epitaxial structure of the semiconductor device comprises: a substrate; and an epitaxial layer located on one side of the substrate, the epitaxial layer comprising at least a first sub-epitaxial layer group, the first sub-epitaxial layer group comprising a first sub-epitaxial layer and a second sub-epitaxial layer arranged in stack; wherein, a surface of one side of the first sub-epitaxial layer away from the substrate comprises a plurality of first dislocation pits, and sidewalls of the first dislocation pits intersect both a plane where the first sub-epitaxial layer is located and a first direction; and the second sub-epitaxial layer covers at least the sidewalls of the first dislocation pits. In the embodiments of the present invention, most of the dislocations in the second sub-epitaxial layer that originally extended upward along the first direction will change their extension direction at the first dislocation pit, and the dislocations bend, thereby reducing most of the dislocations extending upward along the first direction, improving the uniformity of the epitaxial layer, improving crystal quality and product yield, and reducing costs.

What is claimed is: 
     
         1 . An epitaxial structure of a semiconductor device, comprising:
 a substrate; and   an epitaxial layer located on one side of the substrate, the epitaxial layer comprising at least a first sub-epitaxial layer group, the first sub-epitaxial layer group comprising a first sub-epitaxial layer and a second sub-epitaxial layer arranged in stack, the second sub-epitaxial layer being located on one side of the first sub-epitaxial layer away from the substrate; wherein, a surface of one side of the first sub-epitaxial layer away from the substrate comprises a plurality of first dislocation pits, and sidewalls of the first dislocation pits intersect both a plane where the first sub-epitaxial layer is located and a first direction, the first direction being parallel to a direction in which the first sub-epitaxial layer points towards the second sub-epitaxial layer; and the second sub-epitaxial layer covers at least the sidewalls of the first dislocation pits.   
     
     
         2 . The epitaxial structure according to  claim 1 , wherein, along the first direction, depth of the first dislocation pit is h and thickness of the first sub-epitaxial layer is H1;
 where 1/20H1≤h≤½H1.   
     
     
         3 . The epitaxial structure according to  claim 2 , wherein, 5 nm≤h≤60 nm, and H1>100 nm. 
     
     
         4 . The epitaxial structure according to  claim 1 , wherein, along the first direction, depth of the first dislocation pit is h and thickness of the second sub-epitaxial layer is H2;
 where H2>h.   
     
     
         5 . The epitaxial structure according to  claim 1 , wherein, the first sub-epitaxial layer and the second sub-epitaxial layer both comprise one or more of AlN, GaN, AlGaN, and InGaN. 
     
     
         6 . The epitaxial structure according to  claim 5 , wherein, a surface of one side of the first sub-epitaxial layer away from the substrate comprises a plurality of first dislocation pits formed by corrosive gas etching, and along the first direction, depth of the first dislocation pits is h;
 the corrosive gas comprises chlorine gas;   the first sub-epitaxial layer and the second sub-epitaxial layer both comprise GaN, and introduction time of the chlorine gas is t1, where ⅓h≤t1≤h; or,   the first sub-epitaxial layer and the second sub-epitaxial layer comprise AlN and/or AlGaN, and introduction time of the chlorine gas is t2, where ⅔h≤t2≤2h.   
     
     
         7 . The epitaxial structure according to  claim 1 , wherein, the epitaxial layer further comprises a second sub-epitaxial layer group located on one side of the first sub-epitaxial layer group away from the substrate;
 the second sub-epitaxial layer group comprises the second sub-epitaxial layer and a third sub-epitaxial layer, the third sub-epitaxial layer being located on one side of the second sub-epitaxial layer away from the substrate; and   a surface of one side of the second sub-epitaxial layer away from the substrate comprises a plurality of second dislocation pits, and sidewalls of the second dislocation pits intersect both a plane where the second sub-epitaxial layer is located and the first direction; and the third sub-epitaxial layer covers at least the sidewalls of the second dislocation pits.   
     
     
         8 . A method of manufacturing an epitaxial structure of a semiconductor device, for manufacturing the epitaxial structure according to any one of  claims 1 to 7 , comprising:
 providing a substrate;   forming a first sub-epitaxial layer group on one side of the substrate;   wherein, forming a first sub-epitaxial layer group on one side of the substrate comprises:   forming a first sub-epitaxial layer on one side of the substrate;   forming a plurality of first dislocation pits on one side of the first sub-epitaxial layer away from the substrate; sidewalls of the first dislocation pits intersect both a plane where the first sub-epitaxial layer is located and a first direction, the first direction being parallel to a direction in which the first sub-epitaxial layer points towards the second sub-epitaxial layer; and   forming a second sub-epitaxial layer on one side of the first sub-epitaxial layer away from the substrate, the second sub-epitaxial layer covering at least the sidewalls of the first dislocation pits.   
     
     
         9 . The manufacturing method according to  claim 8 , further comprising:
 forming a second sub-epitaxial layer group on one side of the first sub-epitaxial layer group away from the substrate;   wherein, forming a second sub-epitaxial layer group on one side of the first sub-epitaxial layer group away from the substrate comprises:
 forming a plurality of second dislocation pits on one side of the second sub-epitaxial layer away from the substrate; wherein sidewalls of the second dislocation pits intersect both a plane where the second sub-epitaxial layer is located and the first direction; and 
 forming a third sub-epitaxial layer on one side of the second sub-epitaxial layer away from the substrate, the third sub-epitaxial layer covering at least the sidewalls of the second dislocation pits; wherein the second sub-epitaxial layer group comprises the second sub-epitaxial layer and the third sub-epitaxial layer. 
   
     
     
         10 . A semiconductor device, comprising the epitaxial structure according to any one of  claims 1 to 7 , the epitaxial structure comprising a substrate as well as a nucleation layer, a first sub-epitaxial layer group, a channel layer, a spacer layer, a barrier layer and a cap layer sequentially located on one side of the substrate;
 wherein the semiconductor device further comprises:   a source and a drain located on one side of the barrier layer away from the substrate; and   a gate located on one side of the cap layer away from the substrate, the gate being located between the source and the drain.